Neutron detection efficiency and response functions of a thin neutron silicon sensor with low gamma-ray sensitivity

Response functions of a 60-μm thick neutron silicon sensor to 8-MeV neutrons were obtained experimentally and simulated using a Monte Carlo code. The simulation reproduced the experimental results well, however it was found that the discrepancy was due to insufficient treatment of energy deposition process of both alpha particles and 25Mg nuclei emitted simultaneously from the 28 Si(n,α)25Mg reaction. Here, experimental detection efficiencies were well simulated, within 14% difference for neutron energies of 1.1, 2.5, 5, 8, and 15 MeV. An optimized neutron detection efficiency curve of the neutron sensor by weighting high energy contribution was in good agreement with an ambient-dose-equivalent curve, within a factor of 2 at neutron energies from 2.5 to 100 MeV.